The present invention relates to intravascular catheters, and more particularly to a catheter having metallic reinforcing braiding configured to provide the catheter with radiopaque properties and/or kink resistance.
Several types of catheters are utilized for intravascular treatment. Examples of intravascular catheters include guide catheters, angioplasty catheters, stent delivery devices, angiographic catheters, neuro catheters, and the like.
Guiding catheters are commonly used during coronary angioplasty procedures to aid in delivering a balloon catheter or other interventional medical devices to a treatment site in a coronary vessel. In a routine coronary angioplasty procedure, a guiding catheter is introduced into a peripheral artery and advanced over a guidewire through the aorta until the distal end of the guiding catheter is engaged with the appropriate coronary ostium. Next a balloon dilatation catheter is introduced over the guidewire and through the guiding catheter. The guidewire is advanced past the distal end of the guiding catheter within the lumen of the diseased vessel and manipulated across the region of the stenosis. The balloon dilatation catheter is then advanced past the distal end of the guiding catheter over the guidewire until the balloon is positioned across the stenotic lesion. After the balloon is inflated to dilate the blood vessel in the region of the stenotic lesion, the guidewire, balloon dilatation catheter and guiding catheter are withdrawn.
Guiding catheters typically have preformed bends formed along their distal portion to facilitate placement of the distal end of the guiding catheter into the ostium of a particular coronary artery of a patient. In order to function efficiently, guiding catheters should have a relatively stiff main body portion and soft distal tip. The stiff main body portion gives the guiding catheter sufficient xe2x80x9cpushabilityxe2x80x9d and xe2x80x9ctorqueabilityxe2x80x9d to allow the guiding catheter to be inserted percutaneously into a peripheral artery, moved and rotated in the vasculature to position the distal end of the catheter at the desired site adjacent to a particular coronary artery. However, the distal portion should have sufficient flexibility so that it can track over a guidewire and be maneuvered through a tortuous path to the treatment site. In addition, a soft distal tip at the very distal end of the catheter should be used to minimize the risk of causing trauma to a blood vessel while the guiding catheter is being moved through the vasculature to the proper position. Such a soft tip is described in U.S. Pat. No. 4,531,943. In addition, the inner surface of the guiding catheter should be lubricious to facilitate movement of guidewires, balloon catheters and other interventional medical devices therethrough.
Angiographic catheters can be used in evaluating the progress of coronary artery disease in patients. Angiography procedures are used to view the patency of selected blood vessels. In carrying out this procedure, a diagnostic catheter having a desired distal end curvature configuration may be advanced over a guide wire through the vascular system of the patient until the distal end of the catheter is steered into the particular coronary artery to be examined.
A non-limiting example of an angioplasty catheter is found in U.S. Pat. No. 4,646,742. A non-limiting example of a stent deployment device is found in U.S. Pat. No. 5,201,757.
In that the path taken by intravascular catheters is sometimes tortuous, it is important that an intravascular catheter can be steered by torquing its proximal hub and that the torque be transmitted to the distal end in a smooth, controllable fashion. Moreover, the catheter should have sufficient strength in the longitudinal direction so as not to kink or fold as it is advanced through the vascular system. It should also possess a lubricious core lumen to facilitate passage of a guidewire or possibly another catheter or device therethrough.
It is also a desirable feature of certain intravascular catheters that it possess a relatively large lumen to allow fluids, such as radiopaque contrast fluid to be injected therethrough and out the distal end so that the area of the vascular system under investigation can be viewed fluoroscopically.
It is also a desirable feature of certain intravascular catheters that it possess radiopaque and/or kink resistance qualities.
The desirable properties of a catheter having a relatively small O.D. and a relatively large I.D. dictates a relatively thin wall. To maintain the desired torqueability and pushability characteristics of a thin wall catheter calls for considerable ingenuity in the formulation of the materials employed and the constructional techniques utilized.
In accordance with the present invention there is provided an intravascular catheter with an elongated tubular body having a proximal portion, a distal portion and a lumen extending therebetween. The tubular body has a first layer defining the lumen, the first layer made of a polymer having a coefficient of friction of less than about 0.50; a second layer disposed about the first layer, the second layer made of a polymer selected from polyetherester elastomer, polybutylene terephthalate, and combinations thereof; and a reinforcing means. The first layer may be a polymer selected from polytetrafluoroethylene, polyvinylidene fluoride, and polyamide, and may be a polymer having a kinetic coefficient of friction (steel on polymer) less than about 0.35, and preferably less than about 0.10. The first layer may consist essentially of polytetrafluoroethylene. The second layer may have a durometer of from about 30 D-90 D, and may be from about 38 D-74 D. In one embodiment, the second layer will preferably be about 30 D at the distal end of the bodystock and about 90 D at the proximal end of the bodystock. The second layer may be polyetherester blended with polybutylene terephthalate such as about 10-94 weight percent polybutylene terephthalate. The second layer may be have about 8-12 weight percent polyetherester and about 88-92 weight percent polybutylene terephthalate. The reinforcing means may be totally embedded between the first layer and the second layer, or substantially embedded in the second layer. The reinforcing means may be a braided metal mesh of filaments extending from the proximal portion of the tubular body toward the distal portion of the tubular body by a predetermined distance. The reinforcing means may extend to the distal portion of the catheter. The braided metal mesh may be metal filaments braided in a 1 over 1 pattern or 2 over 2 configuration, and may be made of filaments formed of a metal selected from stainless steel and ELGILOY nickel-cobalt alloy . The reinforcing means may be a polymer forming a mesh, a tube, or a fabric, and the polymer may be carbon fibers or polyaramide. The intravascular catheter may have an annular soft-tip member bonded to the distal end of the tubular body member, and the soft-tip member may be polyetherester elastomer having a durometer less than about 50 D. The intravascular catheter may have an outer diameter in the range of from about 2 French to 24 French, preferably from about 4 French to about 12 French.
In another embodiment of the present invention, the present invention relates to a guide catheter having an elongate tubular body with a proximal portion, a distal portion and a lumen extending therebetween. The tubular body has an outside diameter of from about 4 French to about 12 French and has a first layer forming the lumen and made of polytetrafluoroethylene; a braided metal mesh of filaments at least partially surrounding the inner layer; and a second layer at least partially covering the reinforcing means, the second layer made of a blend of polyetherester elastomer and polybutylene terephthalate. The second layer may have a durometer of from about,38 D-74 D, and may be made of about 10-94 weight percent polybutylene terephthalate. In one embodiment, the second layer will preferably be about 30 D at the distal end of the bodystock and about 90 D at the proximal end of the bodystock. The second layer will preferably be made of about 8-12 weight percent polyetherester and about 88-92 weight percent polybutylene terephthalate. The braided metal mesh may be made of metal filaments braided in a 1 over 1 pattern or 2 over 2 configuration. The intravascular catheter may further include an annular soft-tip member bonded to the distal end of the tubular body member, and the soft-tip member may comprise polyetherester elastomer having a durometer less than about 50 D.
In another embodiment of the present invention, the present invention relates to an intravascular catheter having an elongate tubular body having a proximal portion, a distal portion and a lumen extending therebetween. The tubular body may be made of: (a) polymeric material containing substantially no radiopaque filler; and (b) metallic reinforcing braiding configured with sufficient effective thickness to provide the elongate tubular body with substantial radiopacity. The polymeric material may be a polymer selected from polyetherester elastomer, polybutylene terephthalate, and combinations thereof. The metallic reinforcing braiding may be configured in a one-over-one paired wire construction.
In yet another embodiment of the present invention, an intravascular catheter has an elongate tubular body with a proximal portion, a distal portion and a lumen extending therebetween, and the tubular body is made of: (a) polymeric material containing substantially no radiopaque filler; and (b) metallic reinforcing braiding, wherein the combination of polymeric material comprising substantially no radiopaque filler and metallic braid has an amount of radiopacity which is greater than or equal to the amount of radiopacity which would result from a catheter without metallic reinforcing consisting of polymeric material loaded with 20% barium sulfate, preferably greater than about 30%, more preferably between about 30-40%.